Author Topic: Crank end float?  (Read 3026 times)

Offline beezermacc

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Re: Crank end float?
« Reply #30 on: 19.08. 2015 10:19 »
The .003 'clearance', if we use the correct terminology is 'endfloat', in which case the inner race is clamped to the crankshaft but is free to float with the crankshaft until the rollers hit the shoulder of the main bearing. The inner race must be clamped to the crank or it will spin and wear the axle out, and the shims will wear and drop out.
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Offline Colsbeeza

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Re: Crank end float?
« Reply #31 on: 19.08. 2015 11:32 »
Well Chaps,
Sorry I have opened up yet again a can of worms which seems to have been aired several times on the forum in the past, but I think I now understand.
There is a wide range of views on the assembly of the crank. So here is my summary--
I did assemble it correctly all those years ago to 1.5 thou end float, using shims totalling 14 thou, but do not remember whether I fully understood it then.
I did not use any Loctite.
Now that I have it apart, I will remove the inner bearing, recheck the shims and refit the inner bearing using a smear of Loctite 641, which seems to the most suitable Loctite composition. To be safe, if I find that I have used a number of very thin shims, it may be good insurance to replace them with fewer but thicker shims. I see they can be purchased in 2,6 and 10 thou packs on eBay or get some made.
I will duck down to the workshop and check out the drive side cush assembly in next few days, and if you are correct I should see that there is a sleeve over the D/S crank which passes through the outer D/S bearing and locks up against the D/S Inner bearing to clamp the shims tightly between the D/S Inner bearing and the crank web. This will allow the whole crank and cush assembly to move back and forth to the amount of end float, hopefully only about 1 - 1.5 thou.
Given the relatively warm Australian climate, I don't think I need any more end float.
Is my thinking correct.?
I'll get back to you later.
Cheers
Colin
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Offline duTch

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Re: Crank end float?
« Reply #32 on: 19.08. 2015 12:14 »

 Yeah Col, sounds good..except
Quote
which passes through the outer D/S bearing
..but I know what you mean, so all good *wink2*

 NB re my earlier acknowledgement of Richards idea- was done on the phone in some down time on a job...tricky to stay on track, I knew what he meant at the time(maybe I put the wrong sugar in my coffee *eek*)
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
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Online RichardL

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Re: Crank end float?
« Reply #33 on: 19.08. 2015 13:29 »
All,

First, apologies for causing some trouble here with my misread of Trev's post. Now very obvious, in retrospect, that pressure on the rollers is not what's pushing on the inner race. (Bill, I don't think I said that the shims were behind the outer race, but amongst my other errors, so what.) Now, reading Trev's post (and then Beezermacc's) more clearly, end-float existing between the lip of the outer race and the face of the TS bush is also obvious in retrospect. My lingering question, and I am not even going to try to answer it myself, is this: could the inner race creep around the crankshaft regardless of the tightness of the cush nut?

Finally, back to the simple advice that I thought was good way back in this thread. What's wrong with throwing in some Loctite to provide a touch of insurance against a loosening cush nut?

I hope this makes up for my most recent stupidity.

Richard L.

P.S. Forum title demotion forthcoming.

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Online muskrat

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Re: Crank end float?
« Reply #34 on: 19.08. 2015 13:50 »
loose = yes, tight = no
If the nut (no not you) loosens it will move eventually regardless of loctite.
Yes Richard. Lost & Bewildered will be your new title.
Cheers
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Online RichardL

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Re: Crank end float?
« Reply #35 on: 19.08. 2015 15:02 »
it will move eventually regardless of loctite.

My Dear Ozzie Mentor,

Are we talking about the same Loctite? This stuff ( http://www.loctite.com.au/3319_AUE_HTML.htm?nodeid=8797924360193 ) is not supposed to let go until you put 250ÂșC directly on it.

Richard L.

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Online bsa-bill

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Re: Crank end float?
« Reply #36 on: 19.08. 2015 16:48 »
right then, apologies for misinterpreting various aspects of this thread if needed.
beezermacc, I assumed by clamping you meant laterally in which case no float, but I'm going to be in there shortly so better get it sorted in me mind.
Richard - no you most certainly did not say the shims were behind the outer race, I sort of read that in with the clearance between the outer bit.
 
Quote
could the inner race creep around the crankshaft regardless of the tightness of the cush nut?
this morning I was sure that would be a yes - now  *smile*
btw way I'm still pondering your forum binge posting  *conf*
All the best - Bill
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1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online RichardL

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Re: Crank end float?
« Reply #37 on: 19.08. 2015 17:51 »
Richard - no you most certainly did not say the shims were behind the outer race, I sort of read that in with the clearance between the outer bit.

No issue, at all. Who could blame you while it was nested amongst my actual misunderstandings.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Offline East_Coast_BSA

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Re: Crank end float?
« Reply #38 on: 19.08. 2015 18:07 »
Let's start from the beginning on this! When you build the bottom end you fit the timing side bush and main bearing outer to the crankcase halves. You fit the inner race to the crankshaft - make sure it is tight up against the flywheel. The inner race must be tight on the crankshaft so there is no danger of it sliding out of position when measuring the endfloat. You fit the crankshaft in the crankcase and tighten everything up. You feel for endfloat and take a reading with a dial gauge. The optimum is 1 thou but the dial gauge will indicate more than 1 thou at this stage. You dismantle it all and fit as many shims as necessary behind the main bearing inner race to reduce the endfloat to 1 thou. You build it all up again (with the conrods this time) and check for 1 thou endfloat with the dial gauge. The endfloat is simply the amount of sideways travel allowed between the main bearing outer and timing side bush. As far as endfloat is concerned that's it - job done. 

All the cush and sprocket stuff is a red herring as it is merely a mechanism fitted onto the end of the crankshaft axle outside the main bearing so it cannot have any effect on endfloat. However, the cush system and sprocket float on a splined sleeve and it is this sleeve (and spacer) which must be securely fixed the crankshaft to prevent backlash and wear on the splines of the sleeve and crank. So the nut on the end of the crankshaft has to be really tight and serves to lock in place the inner cush mechanism and main bearing inner to the flywheel. It is sensible to build the cush and sprocket onto the crank, on the bench, before installing the bottom end into the bike as final tightening of the crankshaft nut may disturb the main bearing inner and, therefore, the endfloat...........

This is also my understanding of how everything works.  When I put loctite on my inner bearing, I bolted up everything on the bench (including the cush-drive) before I measured end float.  It was tedious because I had to do it a few times, but I'm pretty confident that it was correct when I installed the engine back into the bike.